In [1]} was proved a unique continuations result for the \(b-\) equation (\(b\in [0,3]\) ) and, more generally, for equations of the type (REF ), with functions \(g\)  and \(G\)  depending only on \(u\)  or \(u_x\) , or both, and \(G\)  is non-negative and vanishes only when \(u=0\) , see [1]}. Following our language, the results in [1]} were established using the existence of (local) solutions and continuity of data-to-solution map. Our theorem REF  in particular, and the results presented in section  in general, generalise these results not only for equations depending on higher order derivatives, but also for systems of equations.
